In an on-pump procedure, the heart is stopped and blood is detoured around both the heart and the lungs, but circulated through the rest of the body. However, the use of heart-lung machines can cause potentially fatal complications. In theory, off-pump surgery should reduce these problems.
The results reported today confirm those of several smaller studies, but many important questions remain unanswered about the off-pump procedure.
"Although this method is intellectually appealing, with many theoretical and practical advantages, there are still major concerns because the technique could have significant complications in both the short and long term," writes Magdi Yacoub, F.R.S., of the Royal Brampton Hospital in London, in an editorial in today’s Circulation.
No off-pump bypass studies have provided long-term survival data, he adds. The technique "is gradually establishing its position in practice, but it should continue to be subject to scrutiny in the foreseeable future."
When fully analyzed, the study led by de Jaegere should expand physicians’ understanding of the safety and efficacy of off-pump bypass surgery. For the trial, researchers at three hospitals in The Netherlands enrolled 281 patients and randomized them to either off-pump or on-pump bypass surgery. The average age of the patients was 61 and just over two-thirds were males. Surgeons stabilized the beating hearts of the off-pump patients with what is called the Octopus Method, which was developed by researchers at Utrecht University Medical Center. This stabilization method limits the movement of a small portion of the heart, which allows a surgeon to operate on it without stopping the organ from beating.
"The method is technically more demanding than on-pump procedures," de Jaegere says.
During surgery, blood transfusions were required by 3 percent of the trial’s off-pump patients and 13 percent of the on-pump group. Tests after their surgeries showed that the amount of a cardiac enzyme released by off-pump patients was 41 percent less on average than the on-pump group, which indicated that off-pump patients suffered less heart damage during surgery. There was no difference in terms of upper heart chamber fibrillation, cardiac arrest or heart failure. After four days, on-pump patients had lost weight but off-pump patients showed a weight gain. Off-pump patients were able to leave the hospital one day earlier, on average, than on-pump patients. One month after their surgery, all the patients were alive. Ninety-three percent of the off-pump and 94.2 percent of the on-pump patients had survived without suffering a heart attack, stroke, or other cardiovascular event requiring another procedure to restore blood flow to their hearts. The difference between the two groups was not statistically significant.
Both groups reported improvement in their quality of life, but again, there was no statistically significant difference between them. The researchers also examined the economics of the two procedures and found that the cost was slightly lower for the off-pump operation, $3,112, compared to $3,535 for the on-pump operation.
Co-authors are Diederik van Dijk, M.D.; Arno P. Nierich, M.D., Ph.D.; Erik W. L. Jansen, M.D., Ph.D.; Hendrik M. Nathoe, M.D.; Willem J. L. Suyker, M.D.; Jan C. Diephuis, M.D.; Wim-Jan van Boven, M.D.; Cornelius Borst, M.D., Ph.D.; Erik Buskens, M.D. Ph.D.; Diederick E. Grobbee, M.D., Ph.D.; and Etienne O. Robles de Medina, M.D., Ph.D.
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